flows cmd pretty print

Change-Id: I29b0971a5a862c602f8cd36f864f173c6d8330d6
diff --git a/core/api/src/main/java/org/onlab/onos/net/flow/instructions/Instructions.java b/core/api/src/main/java/org/onlab/onos/net/flow/instructions/Instructions.java
index ada96a5..1bf5531 100644
--- a/core/api/src/main/java/org/onlab/onos/net/flow/instructions/Instructions.java
+++ b/core/api/src/main/java/org/onlab/onos/net/flow/instructions/Instructions.java
@@ -1,5 +1,6 @@
 package org.onlab.onos.net.flow.instructions;
 
+import static com.google.common.base.MoreObjects.toStringHelper;
 import static com.google.common.base.Preconditions.checkNotNull;
 
 import org.onlab.onos.net.PortNumber;
@@ -47,7 +48,7 @@
      */
     public static L2ModificationInstruction modL2Src(MacAddress addr) {
         checkNotNull(addr, "Src l2 address cannot be null");
-        return new ModEtherInstruction(L2SubType.L2_SRC, addr);
+        return new ModEtherInstruction(L2SubType.ETH_SRC, addr);
     }
 
     /**
@@ -57,7 +58,7 @@
      */
     public static L2ModificationInstruction modL2Dst(MacAddress addr) {
         checkNotNull(addr, "Dst l2 address cannot be null");
-        return new L2ModificationInstruction.ModEtherInstruction(L2SubType.L2_DST, addr);
+        return new L2ModificationInstruction.ModEtherInstruction(L2SubType.ETH_DST, addr);
     }
 
     /**
@@ -87,7 +88,7 @@
      */
     public static L3ModificationInstruction modL3Src(IpPrefix addr) {
         checkNotNull(addr, "Src l3 address cannot be null");
-        return new ModIPInstruction(L3SubType.L3_SRC, addr);
+        return new ModIPInstruction(L3SubType.IP_SRC, addr);
     }
 
     /**
@@ -97,7 +98,7 @@
      */
     public static L3ModificationInstruction modL3Dst(IpPrefix addr) {
         checkNotNull(addr, "Dst l3 address cannot be null");
-        return new ModIPInstruction(L3SubType.L3_DST, addr);
+        return new ModIPInstruction(L3SubType.IP_DST, addr);
     }
 
 
@@ -110,6 +111,12 @@
         public Type type() {
             return Type.DROP;
         }
+
+        @Override
+        public String toString() {
+            return toStringHelper(type()).toString();
+
+        }
     }
 
 
@@ -128,6 +135,11 @@
         public Type type() {
             return Type.OUTPUT;
         }
+        @Override
+        public String toString() {
+            return toStringHelper(type().toString())
+                    .add("port", port).toString();
+        }
     }
 
 }